1. The Field of the Invention
The present disclosure relates generally to surgical instruments, and more particularly, but not necessarily entirely, to an apparatus and method for implanting surgical prostheses during surgery.
2. Description of Related Art
The number of total hip replacement surgeries has increased dramatically in recent years. Hip replacement surgery involves implanting a prosthesis to replace an ailing hip joint. The prosthesis is typically made up of two parts: an acetabulum component, or socket portion, which replaces the acetabulum and a femoral component, which replaces the femoral head. The acetabulum component may in turn comprise a metal shell, hereinafter referred to as an acetabular shell, with a plastic or ceramic inner socket liner, hereinafter referred to as a socket liner.
The steps for replacing the hip begin with the surgeon making an incision over the hip joint. There are several different approaches used to make the incision, usually based on the surgeon's training and preferences. After the incision is made, the ligaments and muscles may be separated to allow the surgeon access to the bones of the hip joint. Once the hip joint is entered, the femoral head may be dislocated from the acetabulum. Then the femoral head may be removed by cutting through the femoral neck with a saw. After the femoral head is removed, the cartilage may be removed from the acetabulum using a power drill and a special reamer. The reamer may be used to form the bone in a hemispherical shape to exactly fit the acetabular shell of the acetabular component. Once the right size and shape is determined for the acetabulum, the acetabular shell may be inserted into place. In the uncemented variety of artificial hip replacement, the acetabular shell may be simply held in place by the tightness of the fit or with screws to hold the metal shell in place. Insertion of the acetabular shell may be done by hand or by use of a hand tool that grips the shell. Often, the surgeon may set the acetabular shell into the acetabulum by impacting it through the use of a mallet and an impaction device. The surgeon may then insert a socket liner into the acetabular shell. Once the acetabular shell and socket liner are in place, the surgeon may then replace the femoral head with a femoral component and the surgeon may reassemble the hip joint. The surgeon may also test the movement of the hip joint before closing the incision.
One of the major difficulties confronting the surgeon during hip replacement surgery is the relatively inaccessible location of the acetabulum making it difficult for the surgeon to correctly position the acetabular components. In the past, the solution has been to make a relatively large incision to allow the surgeon complete and unfettered access to the hip joint. However, from the patient's perspective, a large incision is undesirable as it increases the trauma to the patient and the recovery time.
Attempts have been made in the previously available devices to provide a hand tool to assist in holding and positioning an acetabular shell. U.S. Pat. No. 5,116,339 (granted May 26, 1992 to Glock) discloses an installation tool having an expanding head for engaging the acetabular shell. The acetabular shell is released by contracting the head when the shell is in position. The head is expanded and contracted by means of a threaded shaft with a knob such that rotation of the knob correspondingly expands or contracts the head. U.S. Pat. No. 4,305,394 (granted on Dec. 15, 1981 to Bertuch) discloses an acetabular shell positioning device comprising an interchangeable ball and flange for engaging the inner cavity of the acetabular shell by a mechanical engagement. A coupling rod with a handle is manipulated in order to engage and release the acetabular shell.
U.S. Pat. No. 3,859,992 (granted on Jan. 14, 1975 to Amstutz) discloses a suction-operated holding and positioning instrument for use in inserting an acetabular shell during hip surgery. The Amstutz device includes a permanently affixed shell-engaging head and an external suction source for forming a suction force between the shell-engaging head and the shell. The Amstutz device further provides a port controlled by a mechanical valve for selectively breaking the suction force formed between the shell-engaging head and the shell. The Amstutz device does not appear to be able to be used with cementless acetabular shells that require impaction.
The above devices are characterized by several disadvantages including complicated designs involving several moving parts that both increase manufacturing costs as well as making the device more difficult to use during an operation. In particular, the Amstutz device disadvantageously requires a connection to an external suction source. The Amstutz device further does not allow for interchangeable shell-engaging heads to allow the device to be used with different sized acetabular shells. Finally, it appears that none of the above devices can be used to both implant an acetabular shell and a socket liner.
In addition, the shape of the devices dictate the use of relatively large incisions during surgery. One attempted improvement over the previously available devices to reduce the size of the required incision is disclosed in U.S. Patent Publication Application 2003/0229356 (published Dec. 11, 2003 to Dye). The Dye apparatus includes a curved impaction instrument for aligning and impacting the acetabular component into the acetabulum. The curved shape of the apparatus allows for a minimally invasive incision in the patient.
Similarly, U.S. Patent Publication Application 2003/0050645 (published Mar. 13, 2003 to Parker et al.) discloses a curved impactor having a hollow outer shaft and a flexible drive shaft disposed in the outer shaft. The flexible drive shaft is connected at one end to a coupler, and at the opposite end is a thumb wheel, such that rotation of the thumb wheel rotates the drive shaft and engages the coupler to an acetabular shell.
Unfortunately, despite their advantages, both the Dye and Parker et al. apparatuses still has several shortcomings. In particular, the attachment of the acetabular shell to the device requires a mechanical engagement of the shell to the device. Dye is particularly disadvantageous due to the fact that it does not teach a remote release of the acetabular shell once it is installed in the acetabulum. Parker et al., on the other hand, is disadvantageous due to its overly complicated remote release mechanism.
The prior art is thus characterized by several disadvantages that are addressed by the present disclosure. The present disclosure minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein. The features and advantages of the disclosure will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the disclosure without undue experimentation. The features and advantages of the disclosure may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.